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Mathew S. Rosengart

Mathew S. Rosengart is a shareholder in the Litigation Practice with a focus on commercial, media and entertainment, and white collar defense litigation.

Mathew is a former federal prosecutor, with substantial civil and criminal trial experience. A former law clerk to Justice David H. Souter on the Supreme Court of New Hampshire, he also served as a Supervisory Assistant United States Attorney and Justice Department Trial Attorney, where he prosecuted a broad array of cases ranging from violent crimes to public corruption.

Mathew has served as lead counsel in more than a dozen trials and conducted numerous complex federal grand jury investigations, including several of national and international significance, such as the investigation and prosecution of a United States Cabinet Officer and a central figure in the "China-Gate" federal campaign contribution/espionage cases. He further prosecuted a public corruption case commenced at the request of former Attorney General Janet Reno, in which he conducted examinations of several high-ranking government officials, including senior members of the United States Senate, the Justice Department, and The White House.

Among other honors, Mathew has perennially been recognized as one of the nation’s preeminent entertainment litigators by both The Hollywood Reporter (in its 2014, 2015, 2016, and 2017 “Power Lawyer Report,” listing the industry’s Top-100 attorneys) and Variety (in its 2014, 2015, 2016, 201720182019, and 2020 prestigious “Legal Impact Report,” spotlighting the world's leading attorneys in the entertainment industry).

Mathew has represented a number of well-known and high-profile entertainment and other clients in matters ranging from defamation to breach of contract and related matters, including several Academy-Award-nominated and winning writers, directors, and actors, as well as several noted production companies. He has, for example, obtained the complete, pre-trial dismissal of $100 million of claims against the Touring Company of a major Broadway show; resolved an invasion of privacy and right of publicity lawsuit against an internationally-renowned photographer; represented a noted producer in an internal investigation; obtained the complete, pre-trial dismissal of a breach of contract case brought against an Academy-Award nominated director/producer; obtained the dismissal (in the middle of trial) of an $8 million dollar breach of contract case against an Academy Award-winning writer/director; and resolved a motion picture “cutting rights” dispute on behalf of an Academy Award-winning actor/director.

Additionally, Mathew has represented global financial institutions in various matters, including arbitrations before the NASD and AAA; handled complex FCA cases; conducted complex internal investigations on behalf of Fortune 500 companies; and advised and represented members of senior management in FBI and SEC investigations. He obtained the complete dismissal of a $25 million securities fraud case brought against a major global bank by a large group of investors (after a multi-week trial), served as lead counsel in trials and arbitrations on behalf of an international asset management company, and represented a prominent hedge fund manager in a case involving allegations of fraud and breach of fiduciary duty (which was dismissed).


  • Litigation
  • Media and entertainment litigation
  • White collar criminal defense



  • Trial Attorney, Civil and Criminal Divisions of the United States Department of Justice 
  • Supervisory Assistant United States Attorney, United States Department of Justice 
  • Senior Associate Independent Counsel/Supervisory Assistant United States Attorney, Office of Independent Counsel 
  • Trial Attorney, United States Department of Justice, Criminal Division Campaign Finance Task Force

Recognition & Leadership

  • Listed, Variety, "Legal Impact Report," 2014, 2015, 2016, 2017, 2018, 2019, and 2020
  • Listed, The Hollywood Reporter, "Power Lawyers: Top 100 Most Influential Entertainment Lawyers in America," 2014, 2015, 2016, and 2017
  • Named one of California's Top 100 Trial Lawyers, The National Trial Lawyers
  • Featured, Los Angeles Confidential Magazine, "Power Player"
  • Special Achievement Award for Meritorious Acts of Service, United States Department of Justice
  • Federal Bar Association’s Younger Lawyer Award – Awarded by Panel of Federal Judges to the Top 5 government litigators under age 36
  • Special Act Awards for Outstanding Performance, United States Department of Justice, 1995-1996
  • Commendation, federal prosecution and conviction of defendant in United States v. Sheffield, United States Department of Justice, Bureau of Alcohol Tobacco & Firearms, Internal Affairs
  • Commendation, federal prosecution and conviction of defendant in United States v. Brisbane, United States Department of Justice
  • Board of Governors, Beverly Hills Bar Association, 2020 
  • Adjunct Professor of Law, "Criminal Procedure: Grand Jury Law & Practice," Fordham Law School, 2004-2006 
  • Adjunct Professor of Law, "White Collar Crime," Pepperdine University School of Law, 2007 
  • Faculty, United States Attorney General's National Advocacy Center, lecturing in Trial Practice, 2000
  • Dean's Advisory Council, Tulane University
  • Member, Association of Business Trial Lawyers Los Angeles


  • J.D., cum laude, Boston College Law School
  • B.A., Tulane University
  • California
  • New York
  • U.S. District Court for the Southern District of New York
  • U.S. District Court for the Eastern District of New York
  • U.S. District Court for the Central District of California